This invention relates to an improved quench ring and dip tube assembly for use in combination with a quench tank and gasifier for the production of quench cooled and scrubbed synthesis gas, reducing gas or fuel gas. More specifically, the quench ring and dip-tube assembly is used in the hot effluent gas quench section which is located within a pressure vessel that also contains the gasification section for the partial oxidation of hydrocarbonaceous fuels or slurries of solid carbonaceous fuels.
The Texaco partial oxidation process is a well known process for producing synthesis gas, reducing gas, or fuel gas. In this process, gaseous or liquid hydrocarbonaceous, or solid carbonaceous fuels may be reacted with a free-oxygen containing gas in a refractory lined reaction zone to produce a hot effluent gas stream comprising H.sub.2, CO, CO.sub.2 and at least one material from the group comprising H.sub.2 O, CH.sub.4, N.sub.2, H.sub.2 S, and COS. Depending on the feedstock and operating conditions particulate matter may be entrained in the hot effluent gas stream.
All of the hot raw effluent gas stream may be cooled by direct quenching in water contained in a quench vessel located under the reaction zone such as shown and described in coassigned U.S. Pat. Nos. 2,818,326; 2,871,114 and 2,896,927. Alternatively, all of the hot effluent gas stream may be cooled by indirect heat exchange with a coolant such as shown and described in coassigned U.S. Pat. No. 4,251,228. In another gas cooling procedure, the hot effluent gas stream is split into two separate gas streams. One split gas stream is then cooled by direct quenching in water in a quench tank, and the other split gas stream is cooled in a gas cooler, such as shown and described in coassigned U.S. Pat. No. 3,998,609.
The stream of hot effluent gas which is produced in the upper free-flow refractory lined reaction zone is discharged downward through a bottom outlet in the reaction zone. The central longitudinal axis of the bottom outlet is coaxial with that of the gas generator. The refractory lining at the bottom of the reaction zone is supported by a floor. At least a portion of the effluent gas stream may be then cooled and scrubbed with water by discharging said effluent gas stream down through a connecting passage and then through a coaxial down flowing connecting dip-tube that terminates under a pool of water contained in a quench tank below. In order to prevent the thin-walled dip-tube from warping or being otherwise damaged, water is used to control the metal temperature. Thus, a quench water distribution ring, located at the top of the dip-tube provides a film of water over the inside surface of the dip-tube along its length. Optionally, a coaxial draft tube may surround the dip-tube and provide an annular passage through which the quenched gas may rise. A dip-tube and draft tube in a separate quench tank, that is for example in a steel pressure vessel located downstream from the reaction zone is shown in coassigned U.S. Pat. No. 2,818,326. The use of a dip leg in a quench chamber located in the bottom of a steel pressure vessel that also provides a gas cooler for cooling another split stream of gas is shown in coassigned U.S. Pat. No. 3,998,609. Mounting the quench water distribution ring against the floor of the reactor vessel for cooling same, and directing cooling water against the inside of the dip tube is shown in coassigned U.S. Pat. No. 4,218,423.
With increasingly severe service requirements, including high pressure and the use of feedstocks of high sulfur and high metals content, it has become necessary to improve the design of the quench water distribution ring in order to assure adequate water supply. Analysis of metal samples from failed quench rings indicates sulfur attack upon the quench ring faces. This, in turn, is indicative of high metal temperature, i.e., possibly 1300.degree. F. or higher at the faces exposed to the high temperature synthesis gas. Poor welds are particularly subject to failure. All of the aforesaid coassigned U.S. Patents are incorporated herein by reference.